The present invention relates to a surface shape recognition sensor used to sense a surface shape having fine recesses and projections such as human fingerprints and animal's noseprints and a method of manufacturing the sensor and, more particularly, to a surface shape recognition sensor whose recognition surface is protected and a method of manufacturing the sensor.
With the recent proliferation of the Internet, a great deal of attention has been paid to the importance of authentication. Biometrics, in which authentication is performed by measuring/evaluating biological characteristics, has greatly advanced as a technical field of authentication. Authentication using fingerprints, in particular, has been vigorously studied as an authentication means for measuring/evaluating a physical characteristic that cannot be easily changed. In order to perform authentication by using a fingerprint, the fingerprint is read. Systems for reading fingerprints include various systems such as optical systems and capacitive systems. Except for some of the optical systems, when a fingerprint is to be read, the finger generally touches a fingerprint sensor surface.
In a system in which the fingers are made to touch a fingerprint sensor surface, fingerprint residues including sebum remain on the sensor. With the recent increasing orientation toward cleanliness, many users hate to touch the sensor surface, and hence it is required to take measures against this problem (e.g., fourth-page article of the third evening edition of the Asahi Shimbun published by Tokyosha, Aug. 22, 1999). In addition, a fingerprint shape can be easily collected and reproduced from a fingerprint residue left on the sensor surface by the so-called powder method using aluminum powder like that executed by a crime laboratory. From the viewpoint of tamper resistance as well, it is necessary to take measures against the problem.
Furthermore, fingerprint residues interfere as noise with authentication, and hence degrade the authentication performance of the fingerprint sensor. Under the present circumstances, cleaning and wiping the sensor surface are only measures against these problems. With such measures, however, for example, the sensor cannot be continuously used, thus prosing a serious problem.